The present invention relates to an emergency disconnector for disconnecting a fluid loading and unloading line in an emergency to cut off the flow of a fluid passing therethrough.
Fluid loading and unloading lines are used in such applications as for unloading LNG from an LNG tanker situated alongside a sea berth to a storage tank, or for loading LNG from the storage tank to the LNG tanker.
Under rough weather conditions, the LNG tanker tends to come off of the sea berth due to strong winds or high waves while loading or unloading LNG. In such an emergency, it is necessary that the couplings in the fluid loading and unloading line be disconnected, to sever the loader/unloader on the sea berth from the LNG tanker and to cut off the flow of dangerous LNG against unwanted leakage. To meet such requirements, the fluid loading and unloading line generally includes an emergency line disconnector for disconnecting the line in an emergency situation to quickly stop the fluid flow.
Conventional emergency line disconnectors have suffered from the following shortcomings:
(1) Since fluid flow is cut off after the fluid loading and unloading line has been disconnected, the leakage of a considerable amount of fluid is unavoidable before the fluid flow is cut off; and
(2) Designing the disconnector so as to shorten the cutoff time in order to reduce fluid leakage results in an impact such as water hammer being imposed on the fluid loading and unloading line due to quick fluid cutoff.